Conventionally potato chips are fried in a large kettle in a batch process.
Kettle frying of potato chips results in a firm texture high crunch chip. Commercial kettle frying of potato chips results in U-shaped oil temperature curve. After dropping potato slices into the oil, the oil temperature drops rapidly as the heat required to evaporate the high amount of water in the potatoes is consumed, generally faster than the burner can restore heat to the oil. After much of the water is evaporated, the heat load declines and the oil temperature moves higher. Frying is usually completed at an oil temperature near to, but somewhat below, the starting temperature.
Some typical commercial kettle frying conditions for 0.072" thick potato slices are as follows:
TABLE NO. 1 ______________________________________ Type Potato Starting Temp. (.degree.F.) Russet Burbank Norchip ______________________________________ Starting Oil Temp. (.degree.F.) 300-325 300-335 Lowest Oil Temp. (.degree.F.) 240-270 260-280 Final Oil Temp. (.degree.F.) 275-300 300-315 Frying Time (min.) 7-10 8-12 ______________________________________
Specific frying curves for commercial batches of Russet Burbank potatoes and for Norchip potatoes are as follows:
______________________________________ Run No. I. Russet Burbank Potatoes Loading 55 Lbs. Potatoes/238 Gal. Oil (Cottonseed) Slice Thickness = 0.072"; Potato H.sub.2 O = 78.2% Time (Min.) Oil Temp. (.degree.F.) ______________________________________ 0 305 1 266 2 266 3 267 4 270 5 273 6 283 7.5 284 ______________________________________
______________________________________ Run No. II. Norchip Potatoes Loading 55 Lbs. Potatoes/215 Gal. Oil (Cottonseed) Slice Thickness = 0.075"; Potato H.sub.2 O = 78.8% Time (Min.) Oil Temp. (.degree.F.) ______________________________________ 0 325 1 272 2 278 3 282 4 281 5 286 6 294 7 299 8.5 307 ______________________________________
Russet Burbank potatoes contain higher sugar content and thus produce a darker, sweeter chip. These potatoes are used to make a dark Maui style chip, and when kettle fried, produce a dark, sweeter crunchy chip. Norchips, when kettle fried, produce a lighter colored, less sweet crunchy chip.
Some of the general characteristics of batch kettle frying are:
(a) produces a good firm texture (high crunch) chip, PA1 (b) longer frying time than a standard continuous process, PA1 (c) a U-shaped oil temperature curve during frying, PA1 (d) is labor intensive, i.e., one kettle fryer normally requires 1 man and will produce about 75-150 Lbs./hour of chips, whereas a large continuous fryer may produce 4000 Lbs./hour of chips and require only 2 people to operate it, PA1 (e) produces a darker chip having more hardness than a chip fried in a continuous process.
Accordingly, it is a principal object of this invention to provide a continuous frying process that will produce chips having the quality, texture, color and hardness of chips produced by the batch kettle process.
A further object is to provide a chip frying process which provides higher throughput, plus lower labor costs, than a batch system.
Still another object is to provide a continuous process for producing Maui type potato chips.
These and other objects and advantages will become apparent hereinafter.